Implement previouslyExportedState on HermesRuntimeAgentDelegateNew (#43392)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/43392

## Context

We are migrating to the new Hermes `CDPAgent` and `CDPDebugAPI` APIs in the modern CDP server (previously `HermesCDPHandler`).

## This diff

Wires up `previouslyExportedState` with `CDPAgent`, and re-enables the `ResolveBreakpointAfterReload` integration test.

Changelog: [Internal]

Reviewed By: motiz88

Differential Revision: D54369985

fbshipit-source-id: 5dcb4fe59b8b36b2db9f0385e8487097822e5704